Success on both sides sows fear of Libya civil war

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi sits on a truck with a heavy machine gun after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Rebel fighters have captured the key oil port of Ras Lanouf from the forces of Moammar Gadhafi, in their first military victory in a potentially long, westward march from the east of the country to the capital Tripoli hundreds of miles to the west. (AP Photo/Kevin Frayer)
— AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi sits on a truck with a heavy machine gun after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Rebel fighters have captured the key oil port of Ras Lanouf from the forces of Moammar Gadhafi, in their first military victory in a potentially long, westward march from the east of the country to the capital Tripoli hundreds of miles to the west. (AP Photo/Kevin Frayer)
/ AP

Libyans inspect the site of a massive explosion that occured during the night in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)— AP

Libyans inspect the site of a massive explosion that occured during the night in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)
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A defected Libyan soldier looks for body parts from people that died at the site of a massive explosion that occurred during the night in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)— AP

A defected Libyan soldier looks for body parts from people that died at the site of a massive explosion that occurred during the night in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)
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A Libyan man inspects the site of a massive explosion that occurred during the night in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)— AP

A Libyan man inspects the site of a massive explosion that occurred during the night in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)
/ AP

A defected Libyan soldier looks for body parts from people that died at the site of a massive explosion that occurred during the night in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)— AP

A defected Libyan soldier looks for body parts from people that died at the site of a massive explosion that occurred during the night in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)
/ AP

Libyan doctors wash the body of a man that was killed at site of a massive explosion that occurred during the night, at a hospital in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)— AP

Libyan doctors wash the body of a man that was killed at site of a massive explosion that occurred during the night, at a hospital in Benghazi, Libya, Saturday, March 5, 2011. Hospital officials say an explosion at an ammunition depot in Libya's rebel stronghold of Benghazi on Friday has killed at least 17 people. The blast destroyed one warehouse in the base and damaged a second. (AP Photo/Tara Todras-Whitehill)
/ AP

A Libyan rebel who is part of the forces against Libyan leader Moammar Gadhafi climbs to put a pre-Gadhafi flag on the roof of a government building after fighting against troops loyal to Gadhafi in the oil town of Ras Lanuf, eastern Libya, Saturday, March 5, 2011. Rebel fighters have captured the key oil port of Ras Lanouf from the forces of Moammar Gadhafi, in their first military victory in a potentially long, westward march from the east of the country to the capital Tripoli hundreds of miles to the west. (AP Photo/Kevin Frayer)— AP

A Libyan rebel who is part of the forces against Libyan leader Moammar Gadhafi climbs to put a pre-Gadhafi flag on the roof of a government building after fighting against troops loyal to Gadhafi in the oil town of Ras Lanuf, eastern Libya, Saturday, March 5, 2011. Rebel fighters have captured the key oil port of Ras Lanouf from the forces of Moammar Gadhafi, in their first military victory in a potentially long, westward march from the east of the country to the capital Tripoli hundreds of miles to the west. (AP Photo/Kevin Frayer)
/ AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi put a pre-Gadhafi flag on the gate of a government building after fighting against troops loyal to Gadhafi in the oil town of Ras Lanuf, eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)— AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi put a pre-Gadhafi flag on the gate of a government building after fighting against troops loyal to Gadhafi in the oil town of Ras Lanuf, eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)
/ AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi deface a Libyan flag on a wall after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)— AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi deface a Libyan flag on a wall after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)
/ AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi burn a Libyan flag as another holds a pre-Gadhafi flag after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)— AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi burn a Libyan flag as another holds a pre-Gadhafi flag after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)
/ AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi celebrate after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)— AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi celebrate after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)
/ AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi deface a Libyan flag on a wall after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)— AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi deface a Libyan flag on a wall after capturing the oil town of Ras Lanuf, in eastern Libya, Saturday, March 5, 2011. Witnesses say Libyan rebels have captured the oil port town of Ras Lanouf from pro-Moammar Gadhafi forces, their first military victory in what could be a long, westward march to the capital Tripoli. The witnesses said on Saturday that Ras Lanouf, about 87 miles (140 kilometers) east of the Gadhafi stronghold of Sirte, fell in rebel hands Friday night after a fierce battle with pro-regime forces who later fled. (AP Photo/Kevin Frayer)
/ AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi hold a pre-Gadhafi flag as they celebrate after fighting against troops loyal to Gadhafi and capturing the oil town of Ras Lanuf, eastern Libya, Saturday, March 5, 2011. Rebel fighters have captured the key oil port of Ras Lanouf from the forces of Moammar Gadhafi, in their first military victory in a potentially long, westward march from the east of the country to the capital Tripoli hundreds of miles to the west. (AP Photo/Kevin Frayer)— AP

Libyan rebels who are part of the forces against Libyan leader Moammar Gadhafi hold a pre-Gadhafi flag as they celebrate after fighting against troops loyal to Gadhafi and capturing the oil town of Ras Lanuf, eastern Libya, Saturday, March 5, 2011. Rebel fighters have captured the key oil port of Ras Lanouf from the forces of Moammar Gadhafi, in their first military victory in a potentially long, westward march from the east of the country to the capital Tripoli hundreds of miles to the west. (AP Photo/Kevin Frayer)
/ AP

TRIPOLI, Libya 
Moammar Gadhafi loyalists swept into the opposition-held city closest to Tripoli on Saturday, tightening security around the regime-held capital. To the east, rebel forces captured a key oil port as the country veered toward civil war.

Rebels said government forces had moved in to Zawiya, west of the capital, with tanks and dozens of people had been injured, but they vowed to keep up the fight. One rebel said the hospital was under control of pro-Gadhafi forces so the injured were being taken to a makeshift clinic set up in a mosque or to private homes for treatment.

"The number of people killed is so big. The number of the wounded is so big. The number of tanks that entered the city is big," he said, although he couldn't provide a specific casualty toll.

Opposition forces in the east, meanwhile, advanced west in a push toward Gadhafi's hometown of Sirte, a day after the port city of Ras Lanouf fell to the rebellion.

The contrasting fortunes of the two warring sides suggest that the conflict in Libya could last for weeks and maybe months, with neither side mustering enough military power to decisively defeat the other. The government is fighting fiercely to maintain its hold in Tripoli and surrounding areas and the rebels are pushing their front westward from their eastern stronghold.

Gadhafi, who has led the country virtually unchecked for four decades, has unleashed a violent crackdown against those seeking his ouster, drawing international condemnation and sanctions.

Hundreds have been killed, perhaps more, putting pressure on the international community to do more to stop the crackdown on protests that began on Feb. 15, inspired by successful uprisings in Egypt and Tunisia, its neighbors to the east and west respectively.

President Barack Obama has insisted that Gadhafi must leave and said his administration was considering a full range of options, including the imposition of a "no-fly" zone over Libya.

So far, Gadhafi has had little success in taking back territory, with the entire eastern half of the country and some cities near the capital under rebel control. But the opposition forces have had limited success in marching on pro-Gadhafi areas, leading to a standoff that could last for weeks and maybe months, with neither side mustering enough military power to decisively defeat the other.

Saturday's assault on Zawiya, a city of some 200,000 people just 30 miles (50 kilometers) west of Tripoli, began with a surprise dawn attack by pro-Gadhafi forces firing mortar shells and machine guns.

Witnesses who spoke to The Associated Press by telephone with the rattle of gunfire and explosions in the background said the shelling damaged government buildings and homes. The fighting sparked several fires, sending a cloud of heavy black smoke over the city, and witnesses said snipers were shooting at anybody on the streets, including residents who ventured onto balconies.

Initially, the rebels retreated to positions deeper in the city before they launched a counteroffensive in which they regained some of the lost territory, according to three residents and activists, who spoke on condition of anonymity for fear of reprisals.